gazebo ignition hello world

#gazebo  

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Table of Content

First try

Run gazebo with empty world from install worlds

install worlds

/usr/share/ignition/ignition-gazebo6

ign gazebo empty.sdf -v 4
# -v 4 => verbose

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ign cli

• ign cli hello
• run custom world
• control gui options
• spawn and delete entities from cli

ign command

ign --help
The 'ign' command provides a command line interface to the ignition tools.

  ign <command> [options]

List of available commands :

  help:          Print this help text.
  ...
  gazebo:        Run and manage Gazebo.
  msg:           Print information about messages.
  ...
  topic:         Print information about topics.
  service:       Print information about services.
  ...

ign gazebo command

ign gazebo --help

  -r                           Run simulation on start.                         

  -v [ --verbose ] [arg]       Adjust the level of console output (0~4).        

  --gui-config [arg]           Ignition GUI configuration file to load.         

Environment variables

Variable	Description
IGN_GAZEBO_RESOURCE_PATH	Colon separated paths used to locate resources such as worlds and models.
IGN_GAZEBO_SYSTEM_PLUGIN_PATH	Colon separated paths used to locate system plugins.
for more check	ign gazebo –help

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Custom world.sdf

• load minimal world
• control gui layout
• spawn / delete model from cli

Set ignition resource path

export IGN_GAZEBO_RESOURCE_PATH=/home/user/projects/ign_tutorial/

my_empty.sdf

<sdf version="1.6">
    <world name="empty">
      <physics name="1ms" type="ignored">
        <max_step_size>0.001</max_step_size>
        <real_time_factor>1.0</real_time_factor>
      </physics>
      <gui>
        <plugin filename="GzScene3D" name="3D View">
            <ignition-gui>
            <title>3D View</title>
            <property type="bool" key="showTitleBar">false</property>
            <property type="string" key="state">docked</property>
            </ignition-gui>

            <engine>ogre2</engine>
            <scene>scene</scene>
            <ambient_light>0.4 0.4 0.4</ambient_light>
            <background_color>0.8 0.8 0.8</background_color>
        </plugin>

      </gui>
      <plugin
        filename="ignition-gazebo-physics-system"
        name="ignition::gazebo::systems::Physics">
      </plugin>
      <plugin
        filename="ignition-gazebo-user-commands-system"
        name="ignition::gazebo::systems::UserCommands">
      </plugin>
      <plugin
        filename="ignition-gazebo-scene-broadcaster-system"
        name="ignition::gazebo::systems::SceneBroadcaster">
      </plugin>
      <plugin
        filename="ignition-gazebo-contact-system"
        name="ignition::gazebo::systems::Contact">
      </plugin>

      <light type="directional" name="sun">
        <cast_shadows>true</cast_shadows>
        <pose>0 0 10 0 0 0</pose>
        <diffuse>0.8 0.8 0.8 1</diffuse>
        <specular>0.2 0.2 0.2 1</specular>
        <attenuation>
          <range>1000</range>
          <constant>0.9</constant>
          <linear>0.01</linear>
          <quadratic>0.001</quadratic>
        </attenuation>
        <direction>-0.5 0.1 -0.9</direction>
      </light>

      <model name="ground_plane">
        <static>true</static>
        <link name="link">
          <collision name="collision">
            <geometry>
              <plane>
                <normal>0 0 1</normal>
                <size>100 100</size>
              </plane>
            </geometry>
          </collision>
          <visual name="visual">
            <geometry>
              <plane>
                <normal>0 0 1</normal>
                <size>100 100</size>
              </plane>
            </geometry>
            <material>
              <ambient>0.8 0.8 0.8 1</ambient>
              <diffuse>0.8 0.8 0.8 1</diffuse>
              <specular>0.8 0.8 0.8 1</specular>
            </material>
          </visual>
        </link>
      </model>

    </world>
  </sdf>

• Everything control by plugin

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Spawn and remove models

user-commands-system

Allow user control from cli

<plugin
    filename="ignition-gazebo-user-commands-system"
    name="ignition::gazebo::systems::UserCommands">
</plugin>

ign service / msg command

• # list services
  ign service --list
  ...
  /world/empty/create
  ...
  /world/empty/remove
  ...
  
  
  # more info about the service
  ign service --info --service /world/empty/remove
  # result
  Service providers [Address, Request Message Type, Response Message Type]:
    tcp://172.18.0.1:45365, ignition.msgs.Entity, ignition.msgs.Boolean
  
  # Service has two type of message
  # request: ignition.msgs.Entity
  # response: ignition.msgs.Boolean
  
  # message fields
  ## serach for boolean msg
  ign msg --list | grep Boolean
  ign_msgs.Boolean
  
  # show msg fields with --info argument
  user@lap2:~/projects/blog$ ign msg --info ign_msgs.Boolean
  Name: ignition.msgs.Boolean
  File: ignition/msgs/boolean.proto
  
  message Boolean {
    .ignition.msgs.Header header = 1;
    bool data = 2;
  }
  

Spawn SDF

using ign service to Spawn and remove entities

from SDF file

ign service -s /world/empty/create --reqtype ignition.msgs.EntityFactory --reptype ignition.msgs.Boolean --timeout 300 --req 'sdf_filename: "models/my_ball/model.sdf" pose: {position: {z: 5}} name: "new_name"'

from SDF string

Remove

ign service -s /world/empty/remove \
--reqtype ignition.msgs.Entity \
--reptype ignition.msgs.Boolean \
--timeout 300 \
--req 'name: "new_name" type: MODEL'

models/my_ball/model.sdf

<sdf version="1.6">
    <model name="spawned_model">
        <link name="link">
            <visual name="visual">
                <geometry>
                    <sphere>
                        <radius>2.0</radius>
                    </sphere>
                </geometry>
            </visual>
            <collision name="visual">
                <geometry>
                    <sphere>
                        <radius>2.0</radius>
                    </sphere>
                </geometry>
            </collision>
        </link>
    </model>
</sdf>

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